The Global Climate Observing System (GCOS) has developed Climate Monitoring Principles that set out a general guidelines to achieve observations, addressing key satellite-specific operational issues.

Essential Climate Variables
GCOS has identified a set of 50 climate system variables, or Essential Climate Variables (ECVs).
The ECVs are more than a list of variables or groups of related variables for which observations and data products are required to support climate monitoring, forecasting, research, service provision and policy.